Methods which permit real time detection of lead ions (Pb2+) and other metal ions are very important in the fields of environmental monitoring, clinical toxicology, wastewater treatment, and industrial process monitoring and can lead to preventative measures or lower risks associated with metal contaminants. Traditional methods of detecting metal ions are cumbersome, however, often requiring samples collected in the field to be brought back and analyzed in a laboratory setting. Methods are needed for real time detection and monitoring of metal ions in industrial and biological systems.
Fluorescence spectroscopy is a technique well suited for detection of very small concentrations of analytes. Fluorescence provides significant signal amplification, since a single fluorophore can absorb and emit many photons, leading to strong signals even at very low concentrations. In addition, the fluorescence time-scale is fast enough to allow real-time monitoring of concentration fluctuations. Fluorescent properties only respond to changes related to the fluorophore, and therefore can be highly selective.
Commercially available fluorimeters, designed to measure fluorescence signals, however, are typically bulky, heavy, require an AC input voltage or current for power, and are ill-suited for use in the field. Such fluorimeters typically require significant sample preparation, and often as many as twelve or more steps to obtain an analytic result, which generally must be carried out in a laboratory setting. In addition, many if not all commercially available fluorimeters are incapable of measuring extremely small concentrations of analytes such as lead, in the parts per billion (“ppb”) range. In many instances, new environmental laws and regulations requiring testing to the level of ppb, such as newer regulations being promulgated by the U.S. Environmental Protection Agency (“EPA”). Accordingly, a need remains for a portable fluorimeter apparatus and system which is highly sensitive, capable of detecting analytes in the parts per billion range, and which is suited for field use.